Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. It is common to integrate multiple radios into a single communication system. For example, smartphones may have radios to support cellular communication, WiFi, GPS, and Bluetooth, etc., each operating on a different frequency band. Even for systems that have just a single radio, the radio may be a frequency division duplex (FDD) system, in which the transmit (Tx) and receive (Rx) links simultaneously operate on different frequency bands. In these systems, the strongest interference on an Rx signal may be caused by self-jamming leakage from a Tx signal that is simultaneously transmitted by the systems. For example, the Tx signal may leak to the Rx path through the finite isolation between the Tx and Rx paths. Although in a different frequency band, the Tx leakage signal may cause co-channel interference on the intended Rx signal due to non-linearities in the Rx chain. For example, non-linear behavior in the radio frequency (RF) down conversion components: such as low noise amplifier (LNA), mixer, switches, filters, data converters, etc., operating on the Tx leakage signal may generate interference in the Rx frequency band. Another scenario for Tx self-jamming arises when non-linearities present in the transmitter chain generate spectral re-growth such as harmonics of the Tx frequency that fall in the Rx frequency band. The effects of the self-jamming interference due to non-linearities of the Tx or the Rx chains are degradation in the performance of the communication systems.
If the Tx and Rx chains are on the same die, the Tx waveforms that generate the interference are known. Hence, the interference component at the victim Rx chain may be constructed via an adaptive non-linear interference cancellation (NLIC) scheme. For example, the NLIC may generate, based on the known baseband Tx signal, an estimate of the interference in the baseband Rx signal due to the Tx/Rx non-linearities. The Rx chain may remove the estimated interference from the baseband Rx signal to cancel or to mitigate the interference. In this regard, if the aggressor baseband module and victim baseband module are on the same die, NLIC may be implemented by streaming the digital baseband Tx samples from the aggressor baseband module to the victim baseband module via an internal bus or a shared memory.
However, there are situations where it may not be desirable to integrate the Tx and Rx chains, such as the aggressor baseband module and the victim baseband module, on the same die or chip. For example, integration of the Tx/Rx chains from the same radio or different radios on one transceiver die carries the risk that design bugs, design enhancements, or technology upgrade in the Tx or Rx chains may require a re-spin of the entire design. In another example, the bus/memory shared by the aggressor/victim baseband modules may become a limiting factor when the Tx and Rx chains are running at maximum speed or when trying to optimize the performance of the Tx or Rx chain. Furthermore, it may be desirable to pair Tx and Rx chipsets from different vendors together for specific feature-set requirements. Frequently, the aggressor transceiver and the victim transceiver may use different clocks. In these circumstances, the NLIC architecture complexity may become prohibitive as it would require additional modules to compensate for time drift and/or frequency drift between aggressor and victim clocks, increasing the complexity of the design. As such, there is a need for a solution to more easily implement NLIC if the aggressor and victim baseband modules are not on the same chip or on the same die.